With regard to bonding of a semiconductor device, Patent Document 1 discloses a semiconductor apparatus having: a semiconductor device that has a collector electrode on one surface and an emitter electrode on the other surface; and an insulating substrate that has a first electrode interconnect on one surface. The first electrode interconnect of the insulating substrate and the collector electrode of the semiconductor device are connected to each other via a first bonding layer. This first bonding layer is a sintered layer obtained by sintering a bonding material and a reducing agent. The bonding material contains a metal particle precursor that is composed of silver carbonate and the like. The reducing agent is composed of particles of metal carboxylate that have a melting temperature of 200 degrees or more. The semiconductor device and the sintered layer are directly joined to each other as a result of metallic bonding. The technique disclosed in this document is aimed at enabling bonding through metallic bonding at a bonding interface to be realized at a lower temperature.